The invention is concerned with a semiconductor package, and more particularly, to a PGA package.
A sheet of wafer material is able to contain several dozens to several hundreds of chips, on which the same electrical circuits are printed. However, the chip cannot be supplied with electricity from the exterior to transmit or receive electrical signals by itself. In addition, since the chip contains micro-circuits, the chip may be easily damaged by external impacts. A package process is a procedure of making a semiconductor package having physical functions and shapes so that the chip is electrically connected and hermetically packaged to endure the external impacts to thereby render it usable in real life or environment.
Generally, the semiconductor package is classified into a resin sealing package, a tape carrier package (TCP), a glass sealing package, a metal sealing package, etc. These semiconductor packages are also classified into an insert type and a surface mount type depending upon a mounting method. Typically employed as the insert type are a dual in-line package (DIP), a pin grid array (PGA), etc. And typically employed as the surface mounting type are a quad flat package (QFP), a plastic leaded chip carrier (PLCC), a ceramic leaded chip carrier (CLCC), a ball grid array (BGA), etc.
In a conventional semiconductor package, a semiconductor chip is positioned on an accommodating space of a circuit board having a structure that enables a wire pattern to be formed, and the semiconductor chip to be received, and the semiconductor chip to be electrically connected to the wire pattern through bonding wires. Conventionally, the circuit board is made of organic material. That is, the semiconductor chip is adhered on the organic circuit board. The organic material is widely used for the circuit board because its wire pattern can be easily formed and its manufacturing cost is also inexpensive.
However, since the circuit board is formed of the organic material and is in direct contact with the semiconductor chip, thermal characteristics of the semiconductor package may be degraded. In other words, the organic circuit board may be insufficient to discharge a high temperature generated by the semiconductor chip and the circuit board. In addition, the organic circuit board is sensitive to thermal or physical impacts from the exterior.
Meanwhile, a package using ceramic material having improved thermal characteristics over that of the organic material has been proposed and used. However, forming the wire pattern on the ceramic material requires high manufacturing cost in comparison with forming the wire pattern on the organic material. In addition, the ceramic material is also insufficient to provide mechanical stability of the package since it is sensitive to a high external pressure.
In order to solve the problems concerning the mechanical stability of the ceramic material, a metal PGA package using a metal circuit board has been introduced. However, because plural insertion holes should be formed in a metal plate corresponding to a number of pins and an insulating material should fill the respective microscopic insertion holes therein, it causes a process to be complicated and difficult, requiring a high manufacturing cost as well.